1. Field of the Invention
The present invention relates to laser capture microdissection. More particularly, the present invention relates to consumables for laser capture microdissection and to liquid reagent vessels for holding transfer films used in laser capture microdissection.
2. The Prior Art
Diseases such as cancer have long been identified by examining tissue biopsies to identify unusual cells. The problem has been that there has been no satisfactory prior-art method to extract the cells of interest from the surrounding tissue. Currently, investigators must attempt to manually extract, or microdissect, cells of interest either by attempting to mechanically isolate them with a manual tool or through a convoluted process of isolating and culturing the cells. Most investigators consider both approaches to be tedious, time-consuming, and inefficient.
A new technique has been developed which can extract a small cluster of cells from a tissue sample in a matter of seconds. The technique is called laser capture microdissection (LCM). Laser capture microdissection is a one-step technique which integrates a standard laboratory microscope with a low-energy laser and a transparent ethylene vinyl acetate polymer thermoplastic film such as is used for the plastic seal in food product packaging.
In laser capture microdissection, the operator looks through a microscope at a tissue biopsy section mounted on a standard glass histopathology slide, which typically contains groups of different types of cells. A thermoplastic film is placed over and in contact with the tissue biopsy section. Upon identifying a group of cells of interest within the tissue section, the operator centers them in a target area of the microscope field and then generates a pulse from a laser such as a carbon dioxide laser having an intensity of about 50 mW and a pulse duration of between about 50 to about 500 mS. The laser pulse causes localized heating of the thermoplastic film as it passes through it, imparting to it an adhesive property. The cells then stick to the localized adhesive area of the thermoplastic tape directly above them, whereupon the cells are immediately extracted and ready for analysis. Because of the small diameter of the laser beam, extremely small cell clusters may be microdissected from a tissue section.
By taking only these target cells directly from the tissue sample, scientists can immediately analyze the gene and enzyme activity of the target cells using other research tools. Such procedures as polymerase chain reaction amplification of DNA and RNA, and enzyme recovery from the tissue sample have been demonstrated. No limitations have been reported in the ability to amplify DNA or RNA from tumor cells extracted with laser capture microdissection.
Laser capture microdissection has successfully extracted cells in all tissues in which it has been tested. These include kidney glomeruli, in situ breast carcinoma, atypical ductal hyperplasia of the breast, prostatic interepithielial neoplasia, and lymphoid follicles. The direct access to cells provided by laser capture microdissection will likely lead to a revolution in the understanding of the molecular basis of cancer and other diseases, helping to lay the groundwork for earlier and more precise disease detection.
Another likely role for the technique is in recording the patterns of gene expression in various cell types, an emerging issue in medical research. For instance, the National Cancer Institute's Cancer Genome Anatomy Project (CGAP) is attempting to define the patterns of gene expression in normal, pre-cancerous, and malignant cells. In projects such as CGAP, laser capture microdissection is a valuable tool for procuring pure cell samples from tissue samples.
Laser capture microdissection, like all emerging techniques, still has room for improvement. With further refinement of the plastic film and activation by a more tightly focussed laser beam, the technique extraction of single cells can easily be foreseen.
It is therefore an object of the present invention to provide a liquid reagent biological analysis vessel which will facilitate laser capture microdissection analysis.
It is another object of the present invention to provide a liquid reagent biological analysis vessel for use with laser capture microdissection analysis which allows greater automation of the analysis process.
Yet another object of the present invention is to provide a liquid reagent biological analysis vessel for use with laser capture microdissection analysis which is less susceptible to DNA contamination than is presently encountered.